When either brewing or distilling alcohol such as beer or whiskey, grains such as wheat or barley are commonly used. In the brewing process, these grains are stripped of their sugars leaving a high protein, high fiber grain mash. This grain mash is commonly referred to as “spent grain” or “brewer's grain”.
The distillation process produces spent grain through a series of steps beginning with malting. If the distillation process uses barley as the base grain, the process of malting converts plain barley grain into malted barley. The barley is first soaked for between 48 and 72 hours in tanks or steeps and allowed to germinate. The temperature of the germinating barley is carefully controlled, and then the malted barley is spread out and allowed to drain and cool.
The fully germinated malt is next transferred to a malt kiln for drying on a mesh screen over a fire. The malt kiln draws hot air from a furnace through the mesh and malt by way of a chimney effect. The malt is dried and roasted in the kiln at 60° C. for two days and is then ready for the next stage in the distilling process. A method of performing this process is described in Kannenberg et al. U.S. Pat. No. 5,637,336, “PROCESS FOR DRYING MALT”.
The malt contains much detritus or combings, principally rootlets. These are normally removed from the malt and stored for later disposal. The malt is then coarsely ground and becomes known as malt grist. The malt grist is fed into a mash tun where it is combined with a carefully measured quantity of hot water. This completes the conversion of dextrin into maltose and produces a fermentable solution of the malt sugars called wort or worts. Again, after several washings to draw out the malt, the solid residue or draff is removed stored for later disposal. Both the combings and the draff that were removed in this portion of the distilling process are spent grain.
Spent grain is produced in a similar manner in the brewing process. The brewing process is typically divided into several steps; the steps that produce spent grain are mashing and lautering.
Mashing is the process of combining a mix of milled grain, known as the grist (typically malted barley) with water and heating this mixture up to allow enzymes in the malt to break down the starch in the grain into sugars. Sugars created in the mashing process will eventually be the food for the yeast in the fermentation process. Mashing removes most of the proteins, starches and sugars from the grain, leaving behind what is known as spent grain.
Lautering is the process of separating the wort (liquid) from the spent grain. It can be carried out in a mash tun outfitted with a false bottom, a lauter tun, a special-purpose wide vessel with a false bottom and rotating cutters to facilitate flow, a mash filter, or a plate-and-frame filter designed for this kind of separation. Most separation processes have two stages: first wort run-off, during which the extract is separated in an undiluted state from the spent grains; and sparging, in which the extract which remains with the grains is rinsed off with hot water. The spent grain is then typically removed from the process for later disposal.
Whether the spent grain was produced in either a distilling or a brewing process changes little about the grain itself other than determining the flavor and color of the spent grain. Once the spent grain has been removed from either the brewing or distilling process, it is typically considered a waste product. Most producers of alcohol typically with either give the spent grain away for free, or pay to have it disposed of. Larger brewing or distilling operations may have processes in place to process the spent grain such that it can be sold as animal feed. These processes typically include drying the spent grain and then storing it in either open containers or temporary grain silos.
Known processes for drying spent grain include Kepplinger et al. U.S. Pat. No. 6,167,636 “PROCESS FOR THERMALLY UTILIZING SPENT GRAINS”. The process described in Kepplinger et al. is a common process whereby spent grain is tumbled dry in a kiln or furnace type convection dryer that utilizes a natural gas burner as a heat source. However, Kepplinger et al. and other similar methods still view the spent grain as a waste product, in Kepplinger's case, to be burned as a fuel source. Larger breweries and distilleries may already have methods, such as convection tumble drying, in place to dry spent grain so that it can be commoditized and sold as either a fuel source or as animal feed. In this process, rapidly cooling the spent grain prior to drying is not a concern and is not disclosed.
If spent grain is to be used as animal feed it must be at least partially dried. The spent grain may be dried as described above, or may be dried in a mechanical process, such as by a screw press. With either method, there are no requirements for how the grain is handled both before and after the drying process as the regulations for handling the spent grain for animal feed purposes are not very stringent.
It is therefore well known in the art to dry and utilize the spent grain produced in brewing and distilling for fuel or as animal feed. However, the methods commonly employed to prepare the grain would not be either economical or practical for smaller breweries or distilleries. These smaller operations still produce spent grain as a byproduct of alcohol production and have a need for the spent grain to be taken away or disposed of. It is the aim of the present invention to satisfy this need and to provide a system and method for drying, storing, and processing the spent grain into a human consumable product.